[jira] [Commented] (CASSANDRA-9938) Significant GC pauses

["Robbie Strickland (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/CASSANDRA-9938?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14648213#comment-14648213 ] 

Robbie Strickland commented on CASSANDRA-9938:
----------------------------------------------

I found the culprit.  We had a very wide row due to an application error.

> Significant GC pauses
> ---------------------
>
>                 Key: CASSANDRA-9938
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-9938
>             Project: Cassandra
>          Issue Type: Bug
>          Components: Core
>         Environment: Ubuntu 14.04, Java 1.8.0u45
>            Reporter: Robbie Strickland
>              Labels: gc
>         Attachments: gc_log.txt
>
>
> We have an 18-node analytics cluster, running 2.1.7 patched with CASSANDRA-9662.  On a couple of the nodes we are seeing very long GC pauses, especially in old gen, and little space is reclaimed.  Eventually these nodes OOM:
> {code}
> ERROR [SharedPool-Worker-167] 2015-07-30 00:36:20,746 JVMStabilityInspector.java:94 - JVM state determined to be unstable.  Exiting forcefully due to: java.lang.OutOfMemoryError: Java heap space
> {code}
> We use G1 with the following settings:
> Max heap = 16G
> New size = 1.6G
> +UseTLAB
> +ResizeTLAB
> +PerfDisableSharedMem
> -UseBiasedLocking
> The nodes in question have average load profiles for the cluster, and caches are disabled on all tables.  There is no obvious difference with the problematic nodes, and no other clear signs of trouble.  Unfortunately we're currently getting an assertion error when trying to get a heap dump, or I would post that.



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